Recently, oil rigs have been designed to be capable of “walking” from a first location on an oilfield to a second location on the same oilfield. It is not uncommon for an oil rig to drill form 2 to 8 holes on a single pad. While some equipment can be fastened to the rig to be moved over to the next hole usually 15 feet away.
Managed Pressure Drilling is a rather new technique used in oil and gas operations. When drilling for oil and gas, one encounters geological formations that have a narrower tolerance for changes in bottom hole pressure. Using MPD is one solution to this problem. In MPD, the annular space is closed to the atmosphere by means of a Rotating Control Device (RCD). A RCD is a pressure-control device used during drilling for the purpose of making a seal around the drill string during its rotation. The RCD is designed to contain hydrocarbons or other wellbore fluids and prevent their release to the atmosphere. The RCD diverts the fluid into a manifold armed with a specialized choke that allows manipulation of the well's bottom hole pressure. Right before breaking connection to add a new stand, the pumps are ramped down. At the same time, the dynamic component of the bottom hole pressure drops and needs to be compensated for, in order to maintain a near-constant bottom hole pressure.
The MPD system typically comprises a manifold and a tank of compressed gas. The tank and manifold are required to move when the rig is moved because if they did not, the following would be very likely to happen: the primary flow line piping would be longer which increase pressure making drilling more challenging; the U-tube (the pipe that connects the separator tank to the rigs mud tanks) would become very long, this is a safety hazard as it would be a suspended load and it could cause the vessel to plug and spill drilling fluid on ground; and the MPD system would be in the way of the rig's catwalk so that side of the rig would not be usable for pipe or casing which is not an ideal situation.
The current systems available in the industry require pickers to stand separator tanks, flare stacks, pumps and/or generators depending on what models are used.
Even with a “walking” rig, the total time for taking down and setting up a Managed Pressure System can take up to 36 hours. Also, having a system which does not require a picker for setting up and taking down a rig in order to move can save a client upwards of 12 to 16 hours of time depending on the system. This is a very tedious task and can take up to 2 days to move all required Managed Pressure Drilling (MPD) equipment. Current MPD systems without the walking park can be lowered and moved with only the use of a bed truck. It is estimated that a move could be reduced to as little as 4 hours for the entire process. By achieving this, the rigs can begin operation sooner and do not have to wait for the time consuming re-installation of the MPD system. A walking MPD system could even reduce moving time more to as little as 1 hour. This system would also remove the need for bed truck on location saving the client even more.
There are currently trailer mounted flare stacks that can stand themselves. Flare stacks are typically employed to burn off flammable gas released by pressure relief valves during unplanned over-pressuring of equipment. Out in the field, flare stacks require about 5 minutes to stand with the use of hydraulics powered by a 12V battery from a vehicle or other source such as a much smaller generator than those which can be towed with a pickup truck.
Some equipment does not move easily and requires the use of cranes or pickers to move MPD equipment first to the side of location allow the rig to move then reposition into the new spot.
Despite the existing prior art, there still exists a need for a robust, reliable system to displace MPD equipment on an oilfield which allows for faster moving and set up and consequently save time and money.